The present invention relates to a mechanism for discharging a sheet and more particularly to a mechanism applicable to, e.g., a printer for discharging a sheet after reversing it.
To better understand the present invention, brief reference will be made to a conventional printer shown in FIG. 10. As shown, the conventional printer includes paper or similar recording medium implemented as a roll 101. A print head 102 prints an image on the paper paid out from the roll 101. A cutter 103 cuts off the printed part of the paper. The cut paper or sheet is directly driven out of the printer. The print head 102 is affixed to a retraction mechanism 106movable up and down. Moreover, the print head 102 and retraction mechanism 106 are fixed to an upper unit 104, which is movable around a turn axis X toward and away from a lower unit 105.
The problem with the retraction mechanism 106 including the print head 102 is that it is heavy and has a number of signal cables and power feed cables connected thereto. Therefore, when considering its weight and cable wiring, it is unsuitable to mount the retraction mechanism 106 on the upper unit 104.
In light of the above, the print head 102 maybe mounted on the lower unit 105 underlying the roll 101. This, however, brings about another problem. That is, the sheet is driven out of the printer face down, i.e., with its printed surface facing downward. Therefore, its print condition cannot be easily confirmed.
To discharge a sheet face up, a mechanism for reversing the sheet before discharging it has been proposed in various forms in the past. Referring to FIG. 11, it shows a specific conventional sheet reversing mechanism. As shown, the conventional mechanism includes a picker roller 110 and a belt 111 for nipping sheets 109 stacked on the belt 111 face down. A drive section, not shown, drives the picker roller 110, the belt 111 and a belt 112 contacting the downstream side of the belt 111 at the same speed in a direction indicated by an arrow. As a result, the sheet 109 is fed to a nip between the belts 111 and 112 while being pressed by the picker roller 110 against the guide 115. The belts 111 and 112 reverse the sheet 109 little by little along the contour of a guide member 113 while conveying it to a guide 114. Consequently, the sheet 109 is positioned on the guide 114 face up.
However, in the configuration shown in FIG. 11, the sheet 109 is conveyed in one direction, turned down, and then conveyed in the other direction different from the above direction. When this configuration is applied to the layout shown in FIG. 10, the paper 109 cannot be discharged in an opposite side to the input side in which it is input. That is, the paper 109 must be output in the same side in which it is input.
It is therefore an object of the present invention to provide a mechanism capable of reversing a sheet on a sheet conveyance path and then discharging it, and capable of outputting the sheet in a side opposite to an input side by conveying it in substantially the same direction. A mechanism for reversing and discharging a sheet of the present invention includes a first roller for conveying the sheet and a second roller for nipping the sheet with the first roller. After an image has been printed on the sheet, a drive mechanism causes the first and second rollers to convey the sheet until the trailing edge of the sheet arrives at a position spaced from the first roller by a preselected distance. Subsequently, the drive mechanism rotates the first roller in the reverse direction and moves the second roller along the circumference of the first roller by a preselected angle in the reverse direction, thereby conveying the sheet to an outlet section.